Advancing workpieces through a sputtering chamber

ABSTRACT

An apparatus for depositing a thin film of tantalum to workpieces includes a sputtering chamber and entrance and exit chambers located at opposite ends of and communicating with the sputtering chamber. Sealing devices are provided for isolating the sputtering chamber from the entrance and exit chambers. A reciprocating conveyor having a central conveyor section located within the sputtering chamber, and first and second conveyor sections, located in the entrance and exit chambers, respectively, and which sections may all be connected together, is provided for advancing workpieces from a first magazine in the entrance chamber, through the sputtering chamber, to a second magazine in the exit chamber.

United States Patent [72] Inventors Charles S. Hammond, Jr.; [56]References Cited Joseph C. Tribble; Robert M. Tribble; Paul UNITEDSTATES PATENTS 21 A I N #2522? 2,583,968 1/1952 Rosseau 263/6 f 3 19683,294,670 12/1966 Charschan etal. 214/174 f ml 3,314,873 4/1967 Lunsford214/17.4

9 [73] Assignee Western Electric Company, Inc. Primary Examiner.l0hn J.Camby New York, N.Y. Artomeysl-l. J. Winegar, R. P. Miller and S.Gundersen ABSTRACT: An apparatus for depositing a thin film of tantalumto workpieces includes a sputtering chamber and entrance and exitchambers located at opposite ends of and communicating with thesputtering chamber. Sealing devices are [54] ES THROUGHA provided forisolating the sputtering chamber from the en- 18 Claims 6 Drawi Fitrance and exit chambers. A reciprocating conveyor having a centralconveyor section located within the sputtering [52] U.S.Cl. 263/6,chamber, and first and second conveyor sections, located in 263/36 theentrance and exit chambers, respectively, and which sec- [51 Int. ClF27b 9/02, tions may all be connected together, is provided foradvancing F27b 9/24 workpieces from a first magazine in the entrancechamber, [50] Field of Search 263/6, 36; through the s utterin chamber,to a second ma azine in the P 8 8 2 14/ l 7.4 exit chamber.

I 1. i l 1 1 ea Me e9 Z Z4 56 A M 1'1 1 l 1 a I f0 I 32PATENTEUJUNISIEIYI I 3,584,847

sum 2 or 4 PATENTED JUN] 5 I97! sum 3 n; 4

PATENTEU JUN 1 5 I97! SHEET W BF 4 ADVANCING WORKPIECES THROUGH ASPUTTERING CHAMBER BACKGROUND OF THE INVENTION I. Field of the InventionIn the manufacture of electrical devices, such as tantalum thin filmresistors, it is desirable to apply a thin film of tan talum to aworkpiece by cathode-sputtering techniques. In order that the sputteringoperation be commercially practicable, workpieces to which the thin filmof tantalum is applied should be processed continuously through anapparatus capable of performing the sputtering operation. Thus, asputtering apparatus which is designed to continuously advanceworkpieces through a sputtering chamber is commercially desirable.

In addition to being designed for continuous processing, the sputteringapparatus should also prevent the ambient atmosphere from affecting theatmosphere inside the sputtering chamber. Thus, a sputtering machinewhich may be completely isolated from the ambient atmosphere is alsocommercially desirable. The sputtering machine should be capable ofadequately preheating the workpieces before advancement thereof into thesputtering chamber. It is also desirable that the speed of advancementof the workpieces through the apparatus be controllable.

2. Description of the Prior Art In the prior art, various sputteringarrangements have been used to apply a thin film of tantalum to aworkpiece. The earliest apparatus used for sputtering included a belljar into which workpieces to be coated with a tantalum film wereinserted. The bell jar apparatus had two primary disadvantages: First,it was not designed for continuous processing of workpieces; and second,the bell jar had to be completely evacuated each time a new batch ofworkpieces were placed inside.

After development of the bell jar sputtering apparatus, sputteringmachines were designed which were capable of continuously processingworkpieces through a sputtering chamber. Some machines utilized asputtering chamber which was, at all times, completely isolated from theambient atmosphere. Such sputtering machines utilized airlocks locatedat opposite ends of the machine for feeding workpieces, one at a time,into the sputtering apparatus and for removing workpieces from thesputtering chamber in the same fashion. Other sputtering machinesemployed a sputtering chamber which was continuously in communicationwith the ambient atmosphere through restricted openings in opposite endsof the sputtering chamber. In such a machine workpieces could becontinuously advanced through the sputtering chamber on a conveyor whichextended between the openings in the opposite ends of the chamber. Therestricted openings were designed such that the ambient atmosphere had aminimal affect upon the atmosphere maintained in the sputtering chamber.

Another type of sputtering machine, which utilized a sputtering chambercompletely isolated from the ambient atmosphere, employed a conveyingarrangement in which magazines were fed into the sputtering chamberthrough airlocks located at entrance and exit sides of the chamber. Oncethe magazines were located within the sputtering chamber, workpieceswere advanced, one at a time, from the magazine at the entrance side ofthe chamber to the magazine at the exit side of the chamber.

Thus, prior art machines capable of continuously processing workpiecesthrough a sputtering chamber completely isolated from the ambientatmosphere require specially designed airlocks located at opposite endsof the chamber and feeding mechanisms associated with the airlocks foradvancing workpieces to and from the exit and entrance locks,respectively. In view of the prior art, a sputtering machine, capable ofcontinuously processing workpieces through a sputtering chambercompletely isolated from the ambient atmosphere, utilizing a singleconveyor for advancing articles therethrough is desirable. Such anapparatus would eliminate the necessity of providing special handlingmechanisms associated with the entrance and exit airlocks to assist aconveyor located within the sputtering chamber to advance workpiecesthrough the apparatus.

SUMMARY OF THE INVENTION The present invention contemplates an apparatusfor moving articles through a treating chamber having a controlledatmosphere, such as a sputtering chamber. The apparatus includes acentral conveyor section and first and second con veyor sectionsextending to and from respective entrance and exit openings of thetreating chamber. When the conveyor sections are connected together,they may be reciprocated to advance articles into and out of thetreating chamber. When the conveyor sections are disconnected, sealingfacilities at the respective entrance and exit openings may be operatedto seal the treating chamber from the ambient atmosphere.

Additionally, the apparatus includes entrance and exit chambers at therespective entrance and exit openings of the treating chamber. Theentrance and exit chambers may themselves be isolated from the ambientatmosphere and provided with respective controlled atmospheres. Thefirst and second conveyor sections are located within the respectiveentrance and exit chambers. Articles may be subjected to preconditioningand post conditioning in the respective entrance and exit chambers, suchas heating and outgassing in the entrance chamber and cooling in theexit chamber, for any desired lengths of time before and after treatmentin the treating chamber.

Further, the apparatus is provided with first and second magazines whichare mounted within the entrance and exit chambers, respectively. In theoperation of the apparatus, the first magazine is loaded with workpiecesto be advanced through the sputtering chamber. The second magazine isprovided for receiving workpieces which have been advanced through thesputtering chamber. The first conveyor section is designed to removeworkpieces from the first magazine and to advance the workpieces to thecentral section of the conveyor. The second conveyor section receivesworkpieces advanced along the central conveyor section and inserts theworkpieces into the second magazine. When the first magazine iscompletely exhausted and the second magazine is completely filled, theconveyor sections are disconnected and the sputtering chamber is sealed.Then the entrance and exit chambers are opened to permit the processedworkpieces to be removed from the second magazine and unprocessedworkpieces to be loaded into the first magazine.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view, partiallyin section, of a sputtering apparatus which operates in accordance withthe principles of the present invention.

FIG. 2 illustrates schematically first and second magazines located inentrance and exit chambers, respectively, of the sputtering apparatus,and a conveyor along which workpieces are advanced from the firstmagazine through a sputtering chamber to the second magazine.

FIG. 3 is an enlarged view of a portion of the conveyor shown in FIG. 2.

FIG. 4 is an elevation view, partially in section, of the-entrancechamber and a first section of the conveyor located therein.

FIG. 5 is a sectional view of the first section of the conveyor takenalong line 55 of FIG. 4.

FIG. 6 is an elevation view, partially in section, of the exit chamberand a second section of the conveyor located therein.

DETAILED DESCRIPTION In FIG. 1, a sputtering apparatus whichincorporates the principles of the present invention is shown. Theapparatus ineludes an entrance chamber 19, a sputtering chamber 21, andan exit chamber 23. The sputtering chamber 21 contains a sputteringcathode for applying a metallic coating, such as tantalum, to workpiecesadvanced through the chamber 21. A first magazine Ml, located in theentrance chamber 19, is provided for receiving unprocessed workpieces tobe advanced through the sputtering apparatus. Surrounding the magazineMI is a plurality of heating elements 20-20. The heating elements 20-20are utilized to raise the temperature of workpieces in the magazine Mlprior to advancement of the workpieces through the apparatus. A secondmagazine M2 is mounted in the exit chamber 23 for receiving processedworkpieces.

An auxiliary heating chamber 24 is located between the entrance chamber19 and the sputtering chamber 21 and communicates with the entrancechamber 19 through a first sealing device 26. The chamber 24 contains aheating element 22 which is used to maintain workpiece temperature atthe level to which the temperature is raised in the entrance chamber 19.Similarly, a chamber 28 is located between the sputtering chamber 21 andthe exit chamber 23 and communicates with the exit chamber through asecond sealing device 29. The chamber 28 provides for initial cooling ofthe workpieces after advancement through the sputtering chamber 21. Theprimary cooling operation is, however, conducted in the exit chamber 23.The chambers 24 and 28 also serve as buffers for the sputtering chamber21 to protect the atmosphere in chamber 21 from being contaminated bythe atmosphere in the entrance and exit chambers 19 and 23,respectively.

As shown in FIG. 4, the first sealing device 26 is provided with a slide26' which may be moved between the entrance chamber 19 and the chamber24 to seal the chambers 19 and 24 from each other. In similar fashion,the second sealing device 29 (FIG. 6) is provided with slide 29' whichmay be moved between the chamber 28 and exit chamber 23 to seal thechambers 23 and 28 from each other.

CONVEYOR Referring to FIGS. 1 and 2, a conveyor 30 is utilized toadvance articles from the entrance chamber 19 through the sputteringchamber 21 to the exit chamber 23. The conveyor 30 comprises threeseparate portions: (1) a central conveyor section 31 which extendsthrough the sputtering chamber 21 and through the buffer chambers 24 and28, respectively; (2) a first conveyor section 32 located within theentrance chamber 19 and extending toward the chamber 24; and (3) asecond conveyor section 33 located in the exit chamber 23 and extendingtoward the chamber 28.

In general, the conveyor 30 includes a pair of stationary parallel guiderails along which workpieces are advanced by a reciprocating advancingmechanism located between the guide rails. As shown in FIGS. 2 and 3,the first section 32 of the conveyor 30 includes a pair of stationaryparallel guide rails 42-42. The guide rails 42-42 have longitudinalgrooves 42-42a% ,fig. 5) formed on the inner sides thereof for receivingand supporting a workpiece for sliding movement along the guide rails42-42. Between the guide rails 42-42, a workpiece-advancing mechanism islocated. The workpiece-advancing mechanism includes a bar 43 (FIG. 3)mounted for reciprocating movement along a path parallel to the guiderails 42-42. The bar 43 comprises a pair of parallel strips 39-39 whichare fastened together by a set of spacers 41-41 located at equaldistances along the strips 39-39.

The guide rails 42-42 (FIG. 4) are supported by wall 19 of the entrancechamber 19 and by a yoke 34 mounted within a tubular section 35 of theapparatus located between the chamber 19 and the sealing device 26. Asshown in FIG. 5, the yoke 34 includes a pair of plates 36 and 36 whichare fitted together about the guide rails 42-42. Projecting from thesides of the plates 36 and 36' are a set of adjustable arms 37-37 whichare used to support the yoke 34 within the tubular section 35. The plate36 is provided with an opening for receiving the bar 43. At the bottomof the opening, a bead 38 of wear-resistant material, such as hardsteel, is provided to support the bar 43 for reciprocating movement. Asimilar bead 38' (FIG. 4) is mounted on the wall 19 of chamber 19 tosupport the bar 43. The yoke 34 also supports a pair of roller bearings40-40 for engaging the sides of bar 43 and guiding the bar 43 in itsreciprocating movement. In addition, a pair of guide plates 40'-40'(FIG. 5) are mounted on the yoke 34 above the bar 43 to confine the bar43 in a desired location in the opening formed in plate 36'.

Referring to FIG. 3, the bar 43 supports a plurality ofworkpiece-engaging fingers 44-44 which are pivotally mounted withinslots 45-45 located between the spacers 41-41. The fingers 44-44 aremounted on pivot pins 44'-44 such that each finger 44, under the effectof gravity, is normally pivoted into a position where one end of thefinger 44 rests upon a stop 46 and the other end projects above the bar43 to engage workpieces to be advanced. When the bar 43 is moved to theleft, as viewed in FIG. 3, the fingers 44-44 engage the edges of theworkpieces located in the path of movement defined by the guide rails42-42 to advance the workpieces along the guide rails 42-42.

In order to impart reciprocating movement to the bar 43, a rack 47 andpinion 48 (FIG. 4) are provided. The rack 47 is secured to the bar 43.The pinion 48 engages the rack 47 and is driven by a motor 49 (FIG. 4)to impart movement to the bar 43.

The second section 33 (FIGS. 2 and 6) of conveyor 30 also includes apair of parallel stationary guide rails 52-52 having longitudinalgrooves 52'-52' formed on the inner sides thereof to receive workpiecesadvanced along the conveyor 30. The guide rails 52-52 are supported bywall 23' of the exit chamber 23 and by a yoke 57 (FIG. 6) which issimilar to yoke 34 shown in FIG. 5. A bar 53, which supports a pluralityof workpiece engaging fingers 54-54, is mounted for reciprocatingmovement in a path parallel to the guide rails 52-52. The bar 53 issupported for reciprocating movement by a wear-resistant bead 58'mounted on wall 23' of chamber 23 and by a similar bead (not shown)mounted on the yoke 57. The fingers 54-54 are pivotally mounted to thebar 53 within slots 55-55 formed in the bar 54 at equal distancestherealong. The fingers 54-54 are arranged to be normally pivoted upwardinto positions to engage workpieces supported by the guide rails 52-52.

The central section 31 (FIG. 2) of the conveyor 30 includes a pair ofparallel guide rails 62-62 having longitudinal grooves 62-62a% ,figs. 4and 6) formed on the inner sides thereof for receiving and supportingworkpieces. As indicated in FIG. 2, the guide rails 62-62 are dividedinto a series of rail sections to allow for longitudinal expansionthereof resulting from the heat generated during the operation of theapparatus. Referring to FIG. 1, the guide rail sections are supported bythe chamber walls through which the rail sections are inserted and byflexible supports located in the center of each of the chambers 21, 24,and 28. A pair of yokes 67 and 68 (FIGS. 4 and 6, respectively) are alsoprovided for supporting the guide rails 62-62.

A bar 63 is mounted between the guide rails 62-62 for reciprocatingmovement in the path parallel to the guide rails 62-62. The bar 63 issupported for reciprocating movement by wear-resistant beads formed onthe yokes 67 and 68 and by similar beads located in the walls ofchambers 21, 24, and 28. The bar 63 also supports a plurality ofworkpiece-engaging fingers 64-64 which are pivotally mounted withinslots 65-65 formed at equal distances along the bar 63. The fingers64-64 are mounted on the bar 63 in such fashion that, under the actionof gravity, the fingers 64-64 are normally pivoted upward into workpieceengaging positions.

Referring to FIG. 4, the guide rails 42-42 are aligned with and spacedfrom the center guide rails 62-62 to permit the slide 26 of the sealingdevice 26 to move therebetween to seal the entrance chamber 19 from theheating chamber 24. Similarly, as shown in FIG. 6, the guide rails 52-52are aligned with and spaced from the center guide rails 62-62 to permitthe slide 29' of the sealing device 29 to move therebetween and seal theexit chamber 23 from the cooling chamber 28.

As shown in FIGS. 1 and 2, the chamber 24 is provided with a pair ofdevices 50-50 for establishing restricted openings through whichworkpieces are advanced during movement along conveyor 30. The devices50-50 are mounted over the guide rails of conveyor 30 and located atopposite sides of the chamber 24. The purpose of the devices 50-50 is toisolate, as effectively as possible, the chambers 19 and 24 from thesputtering chamber 21. Similarly, the chamber 28 is also provided with apair of devices 50-50' for isolating the sputtering chamber 21 from thechambers 23 and 28.

WORKPIECE-ADVANCING MECHANISM The reciprocating mechanism for advancingworkpieces along the guide rails 42-42, 52-52, and 62-62 of the conveyor30, consists of three separate portions; i.e., the reciprocating bars43, 53, and 63 and the associated workpiece-engaging fingers 44-44,54-54, and 64-64, described above. Referring to FIG. 4, the bar 63 isprovided at the end thereof adjacent to the sealing device 26 with alatch 71 pivotally mounted thereon. The latch 71 has a notch 71' formedtherein for engaging a projection 72 extending from the bar 43. Astationary air cylinder 73, located outside the sealing device 26, isprovided for operating the latch 71. A piston rod 74 extending from theair cylinder 73 through a tubular section 75 of the sputtering apparatussupports a member 76 having a projection 76"for engaging an arm 77extending from the latch 71. When the air cylinder 73 is operated tomove the piston rod 74 downward, the projection 76' moves intoengagement with the arm 77 to pivot the latch 71.

In the operation of the apparatus, when the pinion 48 is rotated to movethe bar 43 leftward, as viewed in FIG. 4, the projection 72 on the bar43 moves to a position where it is engaged by the latch 71 to couple thebars 43 and 63 together. Thereafter, reciprocating movement may beimparted to the coupled bars 43 and 63 through the rack 47 and pinion48. The bars 43 and 63 may be uncoupled by returning the bar 63 to itsinitial position (FIG. 4) and operating the air cylinder 73 to pivot thelatch 71 which disengages the projection 72. The bar 43 may be returnedto its initial position without moving the bar 63.

A similar coupling arrangement (FIG. 6) is provided for connecting thebar 53 to the other end of the bar 63. A latch 81, pivotally mounted onthe bar 53, has a notch 81' formed therein for engaging a projection 82formed on the bar 63. A stationary air cylinder 83, having a piston rod84 extending through an outer wall of the sputtering apparatus, isprovided for operating the latch 81. A member 86 is mounted on thepiston rod 84 and is provided with a projection 86' for engaging an arm87 extending from the latch 81. The coupling and uncoupling of the bars53 and 63 byoperation of the latch 81 to engage and disengage theprojection 82 is similar to the operation of the latch 71 and projection72 described above.

Thus, both bars 43 and 53 may be connected to the bar 63 by operation ofthe latches 71 and 81. Workpieces may be then advanced along the pathdefined by guide rails 42-42, 52-52, and 62-62 by impartingreciprocating movement to the coupled bars 43, 53 and 63 through therack 47 and pinion 48 mechanism. When the advancing mechanism, i.e., thecoupled bars 43, 53 and 63, is moved to the left, as viewed in FIGS. 4and 6, the workpiece-engaging fingers 44-44, 54-54 and 64-64 engage theedges of workpieces supported by the guide rails 42-42, 52-52, and62-62, and advance the workpieces to the left. When the leftward strokeof the advancing mechanism is completed, the motion of the coupled bars43, 53 and 63 is reversed.

Upon movement of the advancing mechanism to the right, theworkpiece-engaging fingers 44-44, 54-54 and 64-64 pivot into horizontalpositions to bypass the advanced workpieces. Thus, the workpieces remainin their advanced positions while the advancing mechanism is moved tothe right, as viewed in FIGS. 4 and 6. When the rightward stroke of theadvancing mechanism is completed, the fingers 44-44, 54-54, and 64-64are moved into positions located between the workpieces. The fingers44-44, 54-54 and 64-64 are then able to pivot into the spaces betweenadjacent workpieces by virtue of gravitational forces exerted thereon.Then leftward movement may be imparted to the advancing mechanism torepeat the advancing sequence. In this manner, workpieces are conveyedin step-bystep fashion along the conveyor 30.

ENTRANCE AND EXIT MAGAZINES Referring to FIG. 2, the magazine M1 forreceiving unprocessed workpieces includes a plurality of verticalsupport members 20'-20' having grooves or notches (FIG. 4) formed on theinner sides thereof for receiving and supporting unprocessed workpieces.The workpieces may be in the form of rectangular plates to which a thinfilm of tantalum is to be applied. Alternatively, the support members20'-20' of the magazine M1 may be utilized to receive a plurality ofrectangular pallets upon which small workpieces, such as ceramic bodies,may be supported during advancement through the sputtering apparatus.

An elevating mechanism is provided for raising and lowering the magazineM1 relative to the first section 32 of the conveyor 30. As shown inFIGS. 2 and 4, the elevating mechanism may comprise a screw which isthreaded into an opening formed in the bottom of the magazine M1. Amotor (not illustrated) may be provided to turn the screw therebyraising or lowering the magazine M1.

In preparing the apparatus for a sputtering operation, the magazine M1is initially located in a raised position relative to the conveyorsection 32. With the sealing device 26 operated to seal the chamber 24,the entrance chamber 19 may be opened in order to allow the magazine M1to be loaded with unprocessed workpieces. During the sputteringoperation of the apparatus, the elevating mechanism is operated to lowerthe magazine M1 to feed the workpieces, one at a time, to the conveyorsection 32.

At the opposite end of the sputtering machine, a second magazine M2 islocated within the exit chamber 23. The magazine M2 also includes aplurality of vertical support members 18-18 having grooves or notches(FIG. 6) for receiving and supporting workpieces which have beenadvanced through the sputtering apparatus. An elevating mechanism,similar to that shown in FIG. 4, is provided for raising and loweringthe magazine M2 relative to the conveyor section 33. Prior to theinitiation of the sputtering operation, the magazine M2, as indicated inFIG. 2, is located in a lowered position relative to the conveyorsection 32. During the advancement of workpieces through the sputteringapparatus, the magazine M2 is raised relative to the conveyor section 32to receive processed workpieces, one at a time, from the sputteringsection of the apparatus. When the sputtering operation is completed,the magazine M2 is located in a raised position relativeto the conveyorsection 32 and is completely filled with workpieces. In order tofacilitate the unloading of the magazine M2, the sealing device 29 isoperated to seal the exit chamber 23 from the cooling chamber 28. Thenthe exit chamber 23 may be opened to allow the processed workpieces tobe unloaded from the magazine M2.

OPERATION In the operation of the sputtering apparatus of the presentinvention, the sputtering chamber 21 is maintained at a high level ofevacuation. The buffer chambers 24 and 28 are maintained at levels ofevacuation which are higher than the evacuation level of the sputteringchamber 21, i.e., the pressures in the chambers 24 and 28 is less thanthe pressure in the chamber 21. A predetermined mixture of nitrogen andargon is supplied to the sputtering chamber 21.

Since it is desirable to maintain the atmosphere in the sputteringchamber 21 at a constant level of evacuation and to preventcontamination of the nitrogen and argon mixture, it is necessary toisolate the chambers 21, 24 and 28 from the ambient atmosphere at alltimes. For this reason, the sealing devices 26 and 29 are provided toprevent the ambient atmosphere from entering the chambers 21, 24 and 28when the entrance chamber 19 and the exit chamber 23 are exposed to theambient atmosphere.

Prior to initiation of a sputtering operation, the slides 26 and 29' ofthe sealing devices 26 and 29, respectively, are closed to isolate thesputtering chamber 21 from the entrance chamber 19 and the exit chamber23. At this time, the entrance chamber 19 may be opened to allowworkpieces to be loaded into the magazine M1. The exit chamber 23 mayalso be opened to allow processed workpieces to be removed from themagazine M2.

At the beginning of a sputtering operation, the magazine M1 is locatedin a raised position (FIG. 4) relative to the conveyor section 32 and iscompletely filled with workpieces. The magazine M2 is located in alowered position relative to the conveyor section 33 (FIG. 6).

The entrance chamber 19 and the exit chamber 23 are closed and thenevacuated until the level of pressure therein is equal to the pressuresmaintained in the chambers 24 and 28. The temperature of the workpiecesis raised to a desired level by the heating elements -20. The slides 26'and 29' of the sealing devices 26 and 29, respectively, are then opened.The entrance chamber 19 is thus in communication with the chamber 24 andthe exit chamber 23 is in communication with the chamber 28.

At this point, the bar 43 is advanced to the left, as viewed in FIG. 4,by rotating the pinion 48 in a counterclockwise direction. When the bar43 moves a sufiicient distance to the left, the projection 72 formed onthe bar 43 moves into the notch 71 formed in the latch 71 on the bar 63.The bars 43 and 63 are thus connected by the latch 71. Upon continuedrotation of the pinion 48 to move the bar 43 to the left, the bar 63which is coupled to the bar 43 also moves in this direction. When thebar 63 is moved a sufficient distance, the projection 82 formed on thebar 63 moves into the notch 81' formed in the latch 81 on the bar 53(FIG. 6). The bar 63 is thus connected to the bar 53 by the latch 81.

Since the bars 43, 53 and 63 are connected together, reciprocatingmotion imparted to the bar 43 through the rack 47 and pinion 48 is alsotransmitted to the bars 53 and 63. It is by virtue of this reciprocatingmovement that workpieces are advanced from the magazine M1 through thesputtering apparatus to the magazine M2. During a leftward stroke of theworkpiece advancing mechanism, the fingers 44-44, 54-54, and 64-64engage and advance workpieces along the guide rails 42-42, 52-52 and62-62 of the conveyor 30. The fingers 44-44 mounted on the bar 43advance workpieces from the magazine M1 along the guide rails 42-42.After the workpieces are advanced through the sealing device 26, theworkpieces are received by the guide rails 62-62 and are furtheradvanced by the fingers 64-64 mounted on the reciprocating bar 63.

The workpieces are then advanced through the chamber 24 beneath theheating element 22 which maintains the workpieces of the desiredtemperature. Continued reciprocation of the bar 63 and the fingers 64-64advances the workpieces through the sputtering chamber 21 past asputtering cathode which applies a thin film of tantalum to theworkpieces. Next, the coated workpieces are advanced through the chamber28, beneath a cooling panel 28, where initial cooling of the workpiecestakes place. Upon advancement through the second sealing device 29, theworkpieces are moved to the guide rails 52-52. The workpieces are thenadvanced along the guide rails 52-52 by the operation of thereciprocating bar 53 and the fingers 54-54 mounted thereon. The bar 53and fingers 54-54 advance the workpieces to the magazine M2.

During the reciprocation of the workpiece-advancing mechanism, themagazine M1 is lowered by the elevating mechanism located in theentrance chamber 19 to present workpieces, supported by the magazine M1,one at a time, to the conveyor section 32. At the same time, themagazine M2 is raised by the elevating mechanism located in the exitchamber 23, by one step at a time, to permit workpieces advanced alongthe conveyor section 33 to be received in the magazine M2.

The reciprocation of the workpiece-advancing mechanism is continueduntil all the workpieces originally located in the magazine M1 areadvanced through the sputtering apparatus and received in the magazineM2. After the magazine M2 is completely filled with workpieces, the bar53 is returned to its initial position, as shown in FIG. 6, and the aircylinder 83 is operated to pivot the latch 81 to disconnect the bar 53from the bar 63.

Then the bar 63 is returned to its initial position, as shown in FIG. 4,to locate the arm 77 of the latch 71 adjacent to the member 76 supportedby the piston rod 74. At this point, the air cylinder 73 is operated topivot the latch 71 to disconnect the bar 43 from the bar 63. Then thebar 43 is returned to its initial position without affecting theposition of the bar 63.

After the bars 43, 53 and 63 are disconnected and located in theiroriginal positions, the slides 26 and 29' of the first and secondsealing devices 26 and 29, respectively, are closed to seal the entrancechamber 19 from the chamber 24 and to seal the exit chamber 23 from thechamber 28. The processed workpieces are then allowed to cool in theexit chamber 23.

After the sealing devices 26 and 29 are closed and the workpieces arecooled, the pressure in the exit chamber is raised to atmospheric leveland the exit chamber 23 is opened to permit the processed workpieces tobe unloaded from the magazine M2. It should be noted that the magazineM2, at this time, is located in a raised position relative to theconveyor section 33.

When the processed workpieces have been unloaded from the magazine M2,the sputtering apparatus may then be prepared for a subsequentsputtering operation. The magazine M2 is moved to its original loweredposition relative to the conveyor section 33. The exit chamber 23 isclosed. The entrance chamber 19 is opened and the magazine M1 is movedto its initial raised position relative to the conveyor section 32.

Then as described above, the magazine Ml, may be loaded with unprocessedworkpieces to be advanced through the sputtering apparatus. The entrancechamber 19 is then closed and the sputtering operation described abovemay be repeated to advance the workpieces from the magazine Ml throughthe sputtering apparatus to the magazine M2.

In order to regulate the amount of tantalum deposited on the workpiecesin the sputtering chamber 21, the speed of reciprocation of theworkpiece-advancing mechanism is made variable by providing a controldevice (not shown) for varying the speed of motor 49 (FIG. 4). Byadjusting the speed ofthe motor 49 to a desired value, the thickness ofthe thin film coating of tantalum applied to the workpieces may becontrolled.

In the operation of the sputtering apparatus, it may be desirable tofurther limit communication between the sputtering chamber 21 and bufferchambers 24 and 28 by positioning workpieces within the devices 50 and50 located adjacent to chamber 21 for the time during which the chambers19 and 23 are exposed to the ambient atmosphere. This result may beaccomplished by removing two of the fingers 64-64 from the bar 63, afirst finger 64 which reciprocates through the device 50 located at theexit side of chamber 24 and a second finger 64 which reciprocatesthrough the device 50 located at the entrance side of chamber 28. Withthese two fingers 64-64 removed, the conveyor 30, in advancing the finaltwo workpieces from the magazine Ml, will operate to advance the firstof the workpieces into the device 50 and the last of the workpieces intothe device 50. The workpieces will then remain in these positions untilanother group of workpieces is loaded into the magazine M1 and advancedthrough the apparatus. It

should be noted that the final two workpieces in the magazine M1 willonly be advanced as far as the devices 50 and 50 located adjacent to thesputtering chamber 21.

It should be noted that the above-described apparatus is merelyillustrative of the principles of the present invention. The conveyingsystem described herein is not limited to utilization with an apparatuscapable of performing only sputtering operations. The system may beincorporated in any apparatus where it is desirable to advanceworkpieces through a treating chamber which is isolated from the ambientatmosphere. In addition, the structure of the apparatus and its mode ofoperation may be modified by persons having ordinary skill in the artwithout departing from the scope of this invention.

What we claim is:

1. An apparatus for moving articles through a treating chamber having acontrolled atmosphere maintained therein, which comprises:

a reciprocating conveyor for advancing articles through the treatingchamber, said conveyor including (l) a central conveyor section mountedfor reciprocating movement in the treating chamber and (2) first andsecond conveyor sections, mounted for reciprocating movement at oppositeends of the treating chamber, detachably connected to said centralconveyor section; and

means for sealing the treating chamber from the outside atmosphere whensaid conveyor sections are disconnected.

2. An apparatus for moving articles through a treating chamber havingentrance and exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein, which comprises:

a reciprocating conveyor for advancing articles through the treatingchamber, said conveyor including (1) a central conveyor sectionextending through the treating chamber and mounted for reciprocatingmovement along a path extending between the entrance and exit openingsformed -in the chamber, (2) first and second conveyor sections locatedoutside the treating chamber at opposite ends of and aligned with saidcentral conveyor section and mounted for reciprocating movement alongpaths parallel to the path of reciprocation of said central conveyorsection;

means selectively operable for coupling said first and second conveyorsections together;

means for imparting reciprocating movement to the coupled conveyorsections to advance articles through the treating chamber during forwardmovement of the con-' veyor sections; and means for sealing the entranceand .exit openings of the treating chamber to seal the interior of thechamber from the ambient atmosphere when said conveyor sections areuncoupled.

3. An apparatus for moving articles through a treating chamber havingentrance and exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein, as set forth in claim 2, whichincludes:

means on said conveyor sections for engaging articles to be advancedduring the forward movement of the conveyor sections and for disengagingthe articles during backward movement of said conveyor sections.

4. An apparatus for moving articles through a treating chamber havingentrance and exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein, as set forth in claim 3,wherein:

said article-engaging means comprises a plurality of gravityoperatedfingers, pivotally mounted to the conveyor sections at equal distancesalong said conveyor sections, said fingers being normally urged intoarticle-engaging positions by gravity during forward movement of theconveyor sections and being pivoted to bypass the articles duringbackward movement of said conveyor sections.

5. In an apparatus for moving articles through a treating chamber havingentrance and exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein:

entrance and exit chambers located at opposite ends of and communicatingwith the treating chamber through the entrance and exit openings,respectively; a conveyor for advancing articles from said entrance 5chamber, through said treating chamber to said exit chamber, saidconveyor including 1) a central conveyor section mounted in saidtreating chamber for reciprocating movement in a path extending from theentrance opening to the exit opening, and (2) first and second conveyorsections, mounted in said entrance and exit chambers, respectively, forreciprocating movement in paths parallel to the path of reciprocation ofsaid central conveyor section; means selectively operable for connectingsaid first and second conveyor sections to said central conveyorsection; means for imparting reciprocating movement to the connectedconveyor sections to advance articles through said treating chamberduring forward movement of said conveyor sections; and

means operable when said conveyor sections are disconnected for sealingsaid entrance and exit chambers from said treating chamber. 6. In anapparatus for conveying articles through a treating 4 chamber having acontrolled atmosphere maintained therein:

entrance and exit chambers located at opposite ends of and communicatingwith the treating chamber;

a conveyor track having a center track section extending through thetreating chamber for receiving and guiding articles in movement throughthat chamber, a first track section extending from said entrance chambertoward said center track section and a second track section extendingfrom said exit chamber toward said center track 3 section;

first means located between said entrance chamber and the treatingchamber and mounted to move between said first and center track sectionsfor sealing the treating chamber from said entrance chamber;

second means located between said exit chamber and the treating chambermounted to move between said center and second track sections forsealing the treating chamber from said exit chamber; and

article-engaging means mounted for reciprocating movement along saidtrack sections to move articles from said entrance chamber through thetreating chamber to said exit chamber, said engaging means including acentral portion for engaging articles on said center track section andfirst and second portions separable from said central portion forengaging articles on said first and second track sections, respectively.

7. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, which comprises:

entrance and exit chambers located at opposite ends of and communicatingwith the sputtering chamber through the entrance and exit openings,respectively;

central guide means extending through the sputtering chamber forreceiving and guiding workpieces in movement through that chamber;

first and second guide means located in said entrance and exit chambers,respectively, and aligned with said central guide means in thesputtering chamber;

workpiece-advancing means mounted for reciprocating movement along saidguide means to engage and move workpieces along said guide means toengage and move workpieces along said first guide means in said entrancechamber to said central guide means in the sputtering chamber and thento said second guide means in said exit chamber, said advancing meansincluding a central port on for engaging workpieces on said centralguide means and first and second portions, which may be coupled to saidcentral portion for engaging workpieces on said first and second guidemeans, respectively;

means for imparting reciprocating movement to said workpiece-advancingmeans after the portions thereof are coupled together to advanceworkpieces along said guide means during forward movement of saidworkpiece-advancing means in a direction extending from said entrancechamber toward said exit chamber;

a first sealing device located between said entrance chamber and thesputtering chamber for sealing the sputtering chamber from said entrancechamber when said first and central portions of said workpiece-engagingmeans are uncoupled; and

a second sealing device located between said exit chamber and thesputtering chamber for sealing the sputtering chamber from said exitchamber when the central and second portions of said workpiece-engagingmeans are uncoupled.

8. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, as set forth in claim7, which includes:

a plurality of fingers, pivotally mounted on the portions of saidworkpiece-advancing means at equal distances therealong, for engagingworkpieces on said guide means during forward movement of saidworkpiece-advancing means and for disengaging the workpieces duringbackward movement of said workpiece-advancing means.

9. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, as set forth in claim8, wherein:

said fingers are normally urged into workpiece-engaging positions bygravity during forward movement of said workpiece-advancing means andare pivoted to bypass the advanced workpieces during backward movementof said workpiece-advancing means.

10. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, as set forth in claim7, which includes:

heating means mounted in said entrance chamber for raising thetemperature of workpieces located in said entrance chamber to a desiredlevel prior to advancement of the workpieces into the sputteringchamber.

11. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, as set forth in claim7, which includes:

a first magazine located within said entrance chamber for receiving aplurality of workpieces to be advanced through the sputtering chamber,said first magazine being mounted to move relative to the first portionof said workpiece-advancing mechanism to feed the workpieces, one at atime, to said first portion of said workpiece-advancing mechanism;

a second magazine located with said exit chamber for receivingworkpieces after advancement thereof through the sputtering chamber,said second magazine being mounted to move relative to the secondportion of said workpiece advancing mechanism to remove workpieces, oneat a time, from said second portion of said workpieceadvancingmechanism; and

means for moving said first and second magazines relative to said firstand second portions of said workpiece-advancing mechanism, respectively,to feed workpieces to said workpiece-advancing mechanism in saidentrance chamber and to remove workpieces from said advancing mechanismin said exit chamber.

12. An apparatus for moving articles into a treating chamber having anentrance opening formed therein and having a controlled atmospheremaintained therein, which comprises:

a conveyor for advancing articles through the entrance opening into thetreating chamber, said conveyor inc|uding 1) an internal conveyorsection located inside the treating chamber with one end thereofadjacent to the entrance opening, said internal section being mountedfor reciprocating movement and (2) an external conveyor section locatedoutside the treating chamber with one end thereof adjacent to theentrance opening, said external conveyor section also mounted forreciprocating movement;

means selectively operable for connecting said external conveyor sectionto said internal conveyor section;

means for imparting reciprocating movement to the connected conveyorsections to advance articles from said external conveyor section to saidinternal conveyor section; and

means for sealing the treating chamber from the ambient atmosphere whensaid internal and external conveyor sections are disconnected.

13. In an apparatus for moving articles into a treating chamber havingan entrance opening formed therein and having a controlled atmospheremaintained therein:

an entrance chamber located at one end of and communicating with thetreating chamber through the entrance opening;

a conveyor for advancing articles from said entrance chamber through theentrance opening into said treating chamber, said conveyor including (1)an internal conveyor section located inside the treating chamber withone end thereof adjacent to the entrance opening, said internal conveyorsection mounted for reciprocating movement along a path extending fromthe entrance opening into the treating chamber, and (2) an externalconveyor section located in the entrance chamber with one end thereofadjacent to the entrance opening, said external conveyor section beingmounted for reciprocating movement along a path parallel to the path ofreciprocation of said internal conveyor section;

means selectively operable for coupling said external conveyor sectionto said internal conveyor section;

means for imparting reciprocating movement to the coupled conveyorsections to advance articles from said entrance chamber into thetreating chamber; and

means for sealing said treating chamber from said entrance chamber whensaid internal and external conveyor sections are disconnected.

14. An apparatus for conveying articles, which comprises:

a central conveyor section mounted for reciprocating movement along apath through which articles are to be conveyed;

first and second conveyor sections located adjacent to opposite ends ofthe central conveyor section and mounted for reciprocating movementalong said path;

means selectively operable for connecting said first and second conveyorsections to said central conveyor section; and

means for imparting reciprocating movement to the connected conveyorsections to advance articles, during forward movement of the conveyorsections, from said first conveyor section along said central conveyorsection to said second conveyor section.

15. An apparatus for conveying articles, as set forth in claim 14, whichincludes:

means on said conveyor sections for engaging articles to be advancedduring forward movement of said conveyor sections and for disengagingthe advanced articles during backward movement of said conveyorsections.

16. An apparatus for conveying articles, as set forth in claim 15,wherein:

said article-engagin g means comprises a plurality of gravityoperatedfingers located at equal distances along said conveyor sections whichare urged into article engaging positions by gravity during forwardmovement of the conveyor sections and pivot to bypass the advancedarticles during backward movement ofsaid conveyor sections.

17. In an apparatus for conveying articles:

a first conveyor section mounted for reciprocating movement along a pathin which articles are to be conveyed;

a second conveyor section mounted for reciprocating movement along saidpath and located adjacent to said first conveyor section;

connecting means operated upon movement of said first conveyor sectioninto engagement with said second conveyor section for connecting saidfirst and second conveyor sections; and

means for imparting reciprocating movement to said first

1. An apparatus for moving articles through a treating chamber having acontrolled atmosphere maintained therein, which comprises: areciprocating conveyor for advancing articles through the treatingchamber, said conveyor including (1) a central conveyor section mountedfor reciprocating movement in the treating chamber and (2) first andsecond conveyor sections, mounted for reciprocating movement at oppositeends of the treating chamber, detachably connected to said centralconveyor section; and means for sealing the treating chamber from theoutside atmosphere when said conveyor sections are disconnected.
 2. Anapparatus for moving articles through a treating chamber having entranceand exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein, which comprises: areciprocating conveyor for advancing articles through the treatingchamber, said conveyor incluDing (1) a central conveyor sectionextending through the treating chamber and mounted for reciprocatingmovement along a path extending between the entrance and exit openingsformed in the chamber, (2) first and second conveyor sections locatedoutside the treating chamber at opposite ends of and aligned with saidcentral conveyor section and mounted for reciprocating movement alongpaths parallel to the path of reciprocation of said central conveyorsection; means selectively operable for coupling said first and secondconveyor sections together; means for imparting reciprocating movementto the coupled conveyor sections to advance articles through thetreating chamber during forward movement of the conveyor sections; andmeans for sealing the entrance and exit openings of the treating chamberto seal the interior of the chamber from the ambient atmosphere whensaid conveyor sections are uncoupled.
 3. An apparatus for movingarticles through a treating chamber having entrance and exit openingsformed in opposite sides thereof and having a controlled atmospheremaintained therein, as set forth in claim 2, which includes: means onsaid conveyor sections for engaging articles to be advanced during theforward movement of the conveyor sections and for disengaging thearticles during backward movement of said conveyor sections.
 4. Anapparatus for moving articles through a treating chamber having entranceand exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein, as set forth in claim 3,wherein: said article-engaging means comprises a plurality ofgravity-operated fingers, pivotally mounted to the conveyor sections atequal distances along said conveyor sections, said fingers beingnormally urged into article-engaging positions by gravity during forwardmovement of the conveyor sections and being pivoted to bypass thearticles during backward movement of said conveyor sections.
 5. In anapparatus for moving articles through a treating chamber having entranceand exit openings formed in opposite sides thereof and having acontrolled atmosphere maintained therein: entrance and exit chamberslocated at opposite ends of and communicating with the treating chamberthrough the entrance and exit openings, respectively; a conveyor foradvancing articles from said entrance chamber, through said treatingchamber to said exit chamber, said conveyor including (1) a centralconveyor section mounted in said treating chamber for reciprocatingmovement in a path extending from the entrance opening to the exitopening, and (2) first and second conveyor sections, mounted in saidentrance and exit chambers, respectively, for reciprocating movement inpaths parallel to the path of reciprocation of said central conveyorsection; means selectively operable for connecting said first and secondconveyor sections to said central conveyor section; means for impartingreciprocating movement to the connected conveyor sections to advancearticles through said treating chamber during forward movement of saidconveyor sections; and means operable when said conveyor sections aredisconnected for sealing said entrance and exit chambers from saidtreating chamber.
 6. In an apparatus for conveying articles through atreating chamber having a controlled atmosphere maintained therein:entrance and exit chambers located at opposite ends of and communicatingwith the treating chamber; a conveyor track having a center tracksection extending through the treating chamber for receiving and guidingarticles in movement through that chamber, a first track sectionextending from said entrance chamber toward said center track sectionand a second track section extending from said exit chamber toward saidcenter track section; first means located between said entrance chamberand the treating chamber and mounted to move between said first andcenter track sections for sealing tHe treating chamber from saidentrance chamber; second means located between said exit chamber and thetreating chamber mounted to move between said center and second tracksections for sealing the treating chamber from said exit chamber; andarticle-engaging means mounted for reciprocating movement along saidtrack sections to move articles from said entrance chamber through thetreating chamber to said exit chamber, said engaging means including acentral portion for engaging articles on said center track section andfirst and second portions separable from said central portion forengaging articles on said first and second track sections, respectively.7. An apparatus for advancing workpieces through a sputtering chamberhaving entrance and exit openings formed in opposite sides thereof andhaving a controlled atmosphere maintained therein, which comprises:entrance and exit chambers located at opposite ends of and communicatingwith the sputtering chamber through the entrance and exit openings,respectively; central guide means extending through the sputteringchamber for receiving and guiding workpieces in movement through thatchamber; first and second guide means located in said entrance and exitchambers, respectively, and aligned with said central guide means in thesputtering chamber; workpiece-advancing means mounted for reciprocatingmovement along said guide means to engage and move workpieces along saidguide means to engage and move workpieces along said first guide meansin said entrance chamber to said central guide means in the sputteringchamber and then to said second guide means in said exit chamber, saidadvancing means including a central portion for engaging workpieces onsaid central guide means and first and second portions, which may becoupled to said central portion for engaging workpieces on said firstand second guide means, respectively; means for imparting reciprocatingmovement to said workpiece-advancing means after the portions thereofare coupled together to advance workpieces along said guide means duringforward movement of said workpiece-advancing means in a directionextending from said entrance chamber toward said exit chamber; a firstsealing device located between said entrance chamber and the sputteringchamber for sealing the sputtering chamber from said entrance chamberwhen said first and central portions of said workpiece-engaging meansare uncoupled; and a second sealing device located between said exitchamber and the sputtering chamber for sealing the sputtering chamberfrom said exit chamber when the central and second portions of saidworkpiece-engaging means are uncoupled.
 8. An apparatus for advancingworkpieces through a sputtering chamber having entrance and exitopenings formed in opposite sides thereof and having a controlledatmosphere maintained therein, as set forth in claim 7, which includes:a plurality of fingers, pivotally mounted on the portions of saidworkpiece-advancing means at equal distances therealong, for engagingworkpieces on said guide means during forward movement of saidworkpiece-advancing means and for disengaging the workpieces duringbackward movement of said workpiece-advancing means.
 9. An apparatus foradvancing workpieces through a sputtering chamber having entrance andexit openings formed in opposite sides thereof and having a controlledatmosphere maintained therein, as set forth in claim 8, wherein: saidfingers are normally urged into workpiece-engaging positions by gravityduring forward movement of said workpiece-advancing means and arepivoted to bypass the advanced workpieces during backward movement ofsaid workpiece-advancing means.
 10. An apparatus for advancingworkpieces through a sputtering chamber having entrance and exitopenings formed in opposite sides thereof and having a controlledatmosphere maintained therein, as set forth in claim 7, which includes:heating means mounted in said entrancE chamber for raising thetemperature of workpieces located in said entrance chamber to a desiredlevel prior to advancement of the workpieces into the sputteringchamber.
 11. An apparatus for advancing workpieces through a sputteringchamber having entrance and exit openings formed in opposite sidesthereof and having a controlled atmosphere maintained therein, as setforth in claim 7, which includes: a first magazine located within saidentrance chamber for receiving a plurality of workpieces to be advancedthrough the sputtering chamber, said first magazine being mounted tomove relative to the first portion of said workpiece-advancing mechanismto feed the workpieces, one at a time, to said first portion of saidworkpiece-advancing mechanism; a second magazine located with said exitchamber for receiving workpieces after advancement thereof through thesputtering chamber, said second magazine being mounted to move relativeto the second portion of said workpiece advancing mechanism to removeworkpieces, one at a time, from said second portion of saidworkpiece-advancing mechanism; and means for moving said first andsecond magazines relative to said first and second portions of saidworkpiece-advancing mechanism, respectively, to feed workpieces to saidworkpiece-advancing mechanism in said entrance chamber and to removeworkpieces from said advancing mechanism in said exit chamber.
 12. Anapparatus for moving articles into a treating chamber having an entranceopening formed therein and having a controlled atmosphere maintainedtherein, which comprises: a conveyor for advancing articles through theentrance opening into the treating chamber, said conveyor including (1)an internal conveyor section located inside the treating chamber withone end thereof adjacent to the entrance opening, said internal sectionbeing mounted for reciprocating movement and (2) an external conveyorsection located outside the treating chamber with one end thereofadjacent to the entrance opening, said external conveyor section alsomounted for reciprocating movement; means selectively operable forconnecting said external conveyor section to said internal conveyorsection; means for imparting reciprocating movement to the connectedconveyor sections to advance articles from said external conveyorsection to said internal conveyor section; and means for sealing thetreating chamber from the ambient atmosphere when said internal andexternal conveyor sections are disconnected.
 13. In an apparatus formoving articles into a treating chamber having an entrance openingformed therein and having a controlled atmosphere maintained therein: anentrance chamber located at one end of and communicating with thetreating chamber through the entrance opening; a conveyor for advancingarticles from said entrance chamber through the entrance opening intosaid treating chamber, said conveyor including (1) an internal conveyorsection located inside the treating chamber with one end thereofadjacent to the entrance opening, said internal conveyor section mountedfor reciprocating movement along a path extending from the entranceopening into the treating chamber, and (2) an external conveyor sectionlocated in the entrance chamber with one end thereof adjacent to theentrance opening, said external conveyor section being mounted forreciprocating movement along a path parallel to the path ofreciprocation of said internal conveyor section; means selectivelyoperable for coupling said external conveyor section to said internalconveyor section; means for imparting reciprocating movement to thecoupled conveyor sections to advance articles from said entrance chamberinto the treating chamber; and means for sealing said treating chamberfrom said entrance chamber when said internal and external conveyorsections are disconnected.
 14. An apparatus for conveying articles,which comprises: a central conveyor section mounted for reciprocatingmovement along a path through which articles are to be conveyed; firstand second conveyor sections located adjacent to opposite ends of thecentral conveyor section and mounted for reciprocating movement alongsaid path; means selectively operable for connecting said first andsecond conveyor sections to said central conveyor section; and means forimparting reciprocating movement to the connected conveyor sections toadvance articles, during forward movement of the conveyor sections, fromsaid first conveyor section along said central conveyor section to saidsecond conveyor section.
 15. An apparatus for conveying articles, as setforth in claim 14, which includes: means on said conveyor sections forengaging articles to be advanced during forward movement of saidconveyor sections and for disengaging the advanced articles duringbackward movement of said conveyor sections.
 16. An apparatus forconveying articles, as set forth in claim 15, wherein: saidarticle-engaging means comprises a plurality of gravity-operated fingerslocated at equal distances along said conveyor sections which are urgedinto article engaging positions by gravity during forward movement ofthe conveyor sections and pivot to bypass the advanced articles duringbackward movement of said conveyor sections.
 17. In an apparatus forconveying articles: a first conveyor section mounted for reciprocatingmovement along a path in which articles are to be conveyed; a secondconveyor section mounted for reciprocating movement along said path andlocated adjacent to said first conveyor section; connecting meansoperated upon movement of said first conveyor section into engagementwith said second conveyor section for connecting said first and secondconveyor sections; and means for imparting reciprocating movement tosaid first conveyor section to (1) move said first conveyor section intoengagement with the second conveyor section to connect said sectionstogether and (2) to advance articles from said first conveyor sectionalong said second conveyor section.
 18. In apparatus for conveyingarticles, as set forth in claim 17: means for disabling said connectingmeans to allow said first and second conveyor sections to be separated.